Medical retrieval devices may include devices for removing organic material (e.g., blood clots, tissue, and biological concretions such as urinary, biliary, and pancreatic stones) and inorganic material (e.g., components of a medical device or other foreign matter), which may obstruct or otherwise be present within a body's anatomical lumens. For example, concretions can develop in certain parts of the body, such as in the kidneys, pancreas, and gallbladder. Minimally invasive medical procedures generally involve causing limited trauma to the tissues of a patient, and can be used to dispose of problematic concretions. Lithotripsy and ureteroscopy, for example, are used to treat urinary calculi (e.g., kidney stones) in the ureter of a patient.
Lithotripsy is a medical procedure that uses energy in various forms such as acoustic shock waves, pneumatic pulsation, electrical hydraulic shock waves, or laser beams to break up biological concretions such as urinary calculi (e.g., kidney stones). The force of the energy, when applied either extracorporeally or intracorporeally, usually in focused and continuous or successive bursts, divides a kidney stone into smaller fragments that may be extracted from the body or allowed to pass through urination.
When stones are fragmented within a body tract by a lithotripter, the stone must first be stabilized. Typically, a medical retrieval device, such as a surgical grasper or a metal wire basket, is used to capture a stone in the retrieval assembly. With the stone held in position within the retrieval assembly, a lithotripter, such as a laser lithotriptor, comes into proximity with the stone and the stone is fragmented by the lithotriptor. After the stone is fragmented, the stone fragments can be removed by the same or a different medical retrieval device, or the fragments can be left in the body to be eliminated naturally. With the help of imaging tools such as transureteroscopic video technology and fluoroscopic imaging, the operator of the lithotriptor device can monitor the progress of the medical procedure and terminate treatment when residual fragments are small enough to be voided or removed with minimal trauma.
Retrieval of intracorporeal fragments of urinary calculi can be problematic in that stones and/or stone fragments in the ureter often migrate within the body before, during, and after a lithotripsy procedure. Therefore, a need exists in the art for a retrieval device that facilitates the initial capture of material as well as maintaining capture of material during further positioning and removal of the captured material and retrieval device. In addition, there also exists a need in the art for a retrieval device that facilitates the controlled release of a stone or fragment during a surgical procedure. For example, controlled release of material is often required to reposition a target stone relative to a lithotriptor or release a captured stone of a size too large for removal without fragmentation.
Thus, it is desirable to have configurations for medical retrieval devices that exhibit improved capabilities for sustained capture, controlled release, and limited patient tissue trauma.